Buggy code:
public class SolrCmdDistributor { private static final int MAX_RETRIES_ON_FORWARD = 25 ; public static Logger log = LoggerFactory . getLogger ( SolrCmdDistributor . class ) ; private StreamingSolrServers servers ; private int retryPause = 500 ; private int maxRetriesOnForward = SolrCmdDistributor . MAX_RETRIES_ON_FORWARD ; private List < SolrCmdDistributor . Error > allErrors = new ArrayList < SolrCmdDistributor . Error > ( ) ; private List < SolrCmdDistributor . Error > errors = new ArrayList < SolrCmdDistributor . Error > ( ) ; public static interface AbortCheck { public boolean abortCheck ( ) { } } public SolrCmdDistributor ( UpdateShardHandler updateShardHandler ) { } public SolrCmdDistributor ( StreamingSolrServers servers , int maxRetriesOnForward , int retryPause ) { } public void finish ( ) { } private void doRetriesIfNeeded ( ) { } public void distribDelete ( DeleteUpdateCommand cmd , List < SolrCmdDistributor . Node > nodes , ModifiableSolrParams params ) throws IOException { } public void distribDelete ( DeleteUpdateCommand cmd , List < SolrCmdDistributor . Node > nodes , ModifiableSolrParams params , boolean sync ) throws IOException { } public void distribAdd ( AddUpdateCommand cmd , List < SolrCmdDistributor . Node > nodes , ModifiableSolrParams params ) throws IOException { } public void distribAdd ( AddUpdateCommand cmd , List < SolrCmdDistributor . Node > nodes , ModifiableSolrParams params , boolean synchronous ) throws IOException { } public void distribCommit ( CommitUpdateCommand cmd , List < SolrCmdDistributor . Node > nodes , ModifiableSolrParams params ) throws IOException { servers . blockUntilFinished ( ) ; doRetriesIfNeeded ( ) ; UpdateRequest uReq = new UpdateRequest ( ) ; uReq . setParams ( params ) ; addCommit ( uReq , cmd ) ; <START_BUG> SolrCmdDistributor . log . debug ( ( ( ( "Distrib<seq2seq4repair_space>commit<seq2seq4repair_space>to:" + nodes ) + "<seq2seq4repair_space>params:" ) + params ) ) ; <END_BUG> for ( SolrCmdDistributor . Node node : nodes ) { submit ( new SolrCmdDistributor . Req ( cmd . toString ( ) , node , uReq , false ) ) ; } } void addCommit ( UpdateRequest ureq , CommitUpdateCommand cmd ) { } private void submit ( SolrCmdDistributor . Req req ) { } public static class Req { public SolrCmdDistributor . Node node ; public UpdateRequest uReq ; public int retries ; public boolean synchronous ; public String cmdString ; public Req ( String cmdString , SolrCmdDistributor . Node node , UpdateRequest uReq , boolean synchronous ) { } } public static Callable testing_errorHook ; public static class Response { public List < SolrCmdDistributor . Error > errors = new ArrayList < SolrCmdDistributor . Error > ( ) ; } public static class Error { public Exception e ; public int statusCode = - 1 ; public SolrCmdDistributor . Req req ; } public abstract static class Node { public abstract String getUrl ( ) { } public abstract boolean checkRetry ( ) { } public abstract String getCoreName ( ) { } public abstract String getBaseUrl ( ) { } public abstract ZkCoreNodeProps getNodeProps ( ) { } } public static class StdNode extends SolrCmdDistributor . Node { protected ZkCoreNodeProps nodeProps ; public StdNode ( ZkCoreNodeProps nodeProps ) { } @ Override public String getUrl ( ) { } @ Override public String toString ( ) { } @ Override public boolean checkRetry ( ) { } @ Override public String getBaseUrl ( ) { } @ Override public String getCoreName ( ) { } @ Override public int hashCode ( ) { } @ Override public boolean equals ( Object obj ) { } @ Override public ZkCoreNodeProps getNodeProps ( ) { } } public static class RetryNode extends SolrCmdDistributor . StdNode { private ZkStateReader zkStateReader ; private String collection ; private String shardId ; public RetryNode ( ZkCoreNodeProps nodeProps , ZkStateReader zkStateReader , String collection , String shardId ) { } @ Override public boolean checkRetry ( ) { } @ Override public int hashCode ( ) { } @ Override public boolean equals ( Object obj ) { } } public List < SolrCmdDistributor . Error > getErrors ( ) { } }

Fix:
SolrCmdDistributor . log . debug ( "Distrib<seq2seq4repair_space>commit<seq2seq4repair_space>to:<seq2seq4repair_space>{}<seq2seq4repair_space>params:<seq2seq4repair_space>{}" , nodes , params ) ;